Focusing device for incandescent studio spotlights



. R. ERxcKsoN FOCUSING DEVICE FOR INCANDESCENT STUDIO SPOTLIGHTS Filed Sept. 13, 1938 y Patentedroct. 31, 1939 UNITED 4sx1-rires PATENT I OFFICE l FOCUSING DEVICE FOR INGANDESCENT j STUDIO SPOTLIGHTS, i l

Carl "R; Erickson, West Los'lflngeles,y Calif., as-

signor to Motion Picture -Electric Products, Los Angeles, Calif., a corporation of California Application september 13, 1938, seia1N0.229,6s2

claims. (o1. 240g-44.2) f

This invention relates rgenerally to incandescent spotlights such'as are used in motion picture studios for illumination of sets, and more particularly to focusing devices for the incandescent 5, ,lamp' of such spotlights.

Studio spotlights are ordinarily .provided with any incandescent lamp that is rmovable forwardly and rearwardlyv for `focusing purposes. Various focusing devices have been providedfor so movloging the lamp, suchy devices usuallyl involvingfa lead screw,and in all cases of which I am aware, involving .al rotatable manual operating member. .This rotatable manual operating member is l'frequently inconvenient to manipulate llieunder conditions as encountered under practical `studio conditions. At times the lamp is mounted at a considerable elevation above the floor of the set, on its own standor a wall bracket, and mayr there-fore'not be` easy to reach with the hand. zofl'he. manual focusing 'member of prior lamps ordinarily extends either from one side or from the' back'of the lamp. Frequently, the lamp is so situated that the side or the `back of the lamp, where themanual focusing member is located,

vzlscannot conveniently be reached.

" It is accordingly an object-of the present-inl vention. to'provide an improved focusing device l for. incandescent spotlights, ydesigned to be eX- y ceptionally accessible to the operator kunder all 3Q, B worki-ng, conditions. i

' A further object of the invention is` to provide a focusing device which can be operated, when the lamp issituated at an elevation such that it cannot be reached bythe hand, simply by use of l Lilfmechanisnr is exceptionally simple in character,

and-is at the same ktime exceptionally easy to operate 'and quick toadjust.

y,'lhedetails of the invention will be set forthin the body of the specification, in whichis de- 50,scribed a :present preferred illustrative embodi- `me`nt thereof. Reference for this purpose -is directed to the accompanying drawing, in which: vvlig. 1 is an elevation, partly in section, showing'a' spotlight embodying the focusing mecha- 55 .nism of the present invention;` f

Fig. 2 is a horizontal section taken on line 2-2 of Fig. 1 and Y Fig. 3 is a rear View of the lower portion of the 1amp,lshowinglthe focusing mechanism housing andthe rear focusing lever arm. y

The specific spotlight here shown for illustra tive purposes has a substantially cylindrical or barrel-shaped exterior casing I0, provided with forward andrearward -openings II and I2, respectivelvg; Mounted in forward opening II is a conventional lens I3, while rearward opening I2 is closed Iby aldoorA I4. Secured to the top of the casingis a casting I6 provided with a handle I'I. A focusingmechanism housing 2|] is mounted on the `lower sideof the lampl casing. Thus, as illustratively shown in the drawing, housing comprises a casting; having arms 2I and 22 engagingtheside wallof the casing and secured thereto by screws 23. Housing 20, in the specific forml here shown, comprises front and rear Walls and ,26, respectively, side walls 2l, and a bottom Wall 28. A 'Ihelower portion of lthe lamp casing, inside thefboundaries of housing 20, is removed, so vthat thev interior of the lamp opens to the interior of,v the mechanism housing 2l).v Of course, while the mechanism housing 2l) ofthe present illustrative form yof the invention is shown as comprising a separate casting secured to the lamp y`casing, it may, if desired, be formed as an integral part of the lamp casing, any mechanical construction being suitable which will provide a proper offset-housing spacedvor recessed for accommodating the focusing mechanism on or at the lower: side of the otherwise substantially cyl/indric lamp casing.

The incandescent .lamp is designated generally at 30, and its usual socket at 3l, the latter being mounted ona platform or carriage 32 provided with perforated lugs 33 and 34 which are slidable on a pair of parallel guide rods 36 running longitudinally of thela-mp and mounted at their ends in perforated bosses 38 formed on the forward and rearwardl walls 25 kand 26 of housing 20. Rods 35 are indicated in Fig. 2 as secured vin position by means of I.pins 39 extending through forward bosses 33. As clearly shown, these rods`36 areparallel totheaxis of lens I3, and are in a horizontal plane. It will also be noted that incandescent lamp 301s positioned on the axis of lens I3, Iandis movable along said axis as platform32 is moved `forwardly or rearwardly along rods 36,V y

`Platfor1nx32vis shown furnished with a bracket 35 supporting a small spherical mirror 31 to the -rearof lan1p3il,I VThis mirror serves lthe usual scribed. A focusing lever 40 is provided, comprising aV forwardly projecting arm 4I, a rearwardly projecting arm 42., andan intermediatel hub 43 pivotally mounted in a suitable marmer on lower housing wall 28, as indicated at 43a, at approximately the cent-er of the lamp from front to rear. Extending from hulo 43 of1 leven-4U, atk right angles to arms fil and 42, is a third arm 50,

and an operative connection is providedy between.

said arm and lamp carriagey 32..l Though this connection may be embodiedzin various. forms, a

simple form is here shown comprising a longitudinal slot i in arm 50, anda pin 52- carried by the carriage and engaging in saidf slot. As here illustrativelyshown, this pin 52 is set into an rarm 53 integral'withand-projecting laterally from platform 32. v

Forward and rearward leverarms 4| and 42 project through horizontal slots 55 andy 5%6, respectively, in the forward'andfrearward ends of housing 28,' being `formed on their projecting ends with nger pieces 5l and 58, respectively.

'Movementfrom side to side of either front -finger piece 5'! or rear iinger'piece 53 swings lever' 4t, and thereforel arm 5t), about pivotal mounting ittcasuchmovement of arm 5i! acting through vthe described pin andslotv connection with *they lamp and mirror carriage to cause the ,latter to be lmoved along guiderods 36.

The natural friction'in the mechanism is such that the carriage will not slide along guide rods t@ vas the lamp is tilted forwardly or rearwardly, and will accordingly remain ink any position to which it is moved by the focusing mechanism. "The leverage of the focusing mechanism is s uf-l iicient, however, that the focusing arms may be Veryv easilyfmoved, and vmay be readily moved,

in fact, in casesin which the-lamp is out of reachf of the/hand, simply by engaging a-pro- Jjecting rend ofv the lever witha long stick.` The twooperating'ends of the lever, projecting from the front and rear ends of the lamp, enable the focus of the lamp to be conveniently adjusted, i

regardless of the position in which -it may be `Asituated; Moreover, adjustmentof focus-.may be n accomplished'with exceptionalv rapidity. Finally,

of the members. Also, it is to be-understood that the lamp will roften be' employed in tilted posin tions, in which case the pivot axis. Wouldno A longer Vbe vertical. The expressions in question of course are not restricted againstl suchv tilted positions of use of the lamp, being employed simply for' convenienceV in deiining the direction -of action of the lever withreference to the lamp as a whole,'va'ssuming the lamp to be positioned in ka level position as illustrated inthedrawing.

The expressions employed inthe claims are therefore to be regarded as reading on the lamp re- K gardless ofthe positionto'which it may be tilted in practice, despite the fact that the pivot axis ofthe lever will not y be vertical in such tilted positions of use.

. It is to be'understood that while I have now shown one typical embodiment of the invention', this is for illustrative purposes only, and that various changes in design, structure and arrangement may be made without departing from the spirit and scope of the invention or of the appended claims. 1

l. In an incandescent studio spotlight embodying a lamp casing having' an opening at its forward end: a mechanism housing on the bottom `of and opening inside said lamp casing, a lamp carriage adaptedvt'o support a lamp within said casing, means supporting and guiding said carriage for forward and rearward movement with' reference to saidv lamp casing, a focusing lever within said mechanism housing pivotally mounted on a substantially vertical axis, a slot in a wall of said housing passingA said focusing lever, and

Van operative` interconnection between said focusof and opening inside said lamp, casing, a lamp carriage adapted to supporta lamp within said casing, rneanssupporting and guiding said carwithhorizontally extending slots, a focusing lever.`v

within said vhousing pivotally mounted on a. sub1 stantially verticalV axis, said lever having oppositel-y extending arms projecting through said horizontally extending slots', andan operative in,-

terconnection betweenl said Vfocusing lever andi saidlamp carriage. l

` 3; In anincandescent studio spotlight embodying a lamp. casing having an opening at its for;-

word` end: a mechanism housings on. the'loottomy of and' opening inside said lamp casing, a lamp carriage adapted to support .as lamp lwithin said casing, meanssupporting and' guiding saidcarriage for forward and rearward movement with reference to isai'd' lamp casing, vsaidmechanisml housing having iront and rear walls provided with f horizontally extending slots, a focusing .lever withingsaidhousing pivotally. mounted on a sub-- stantially vertical axis, said lever having oppositelyextendinglarms projecting through said horizontally extending slots, andan operative interconnection between said focusing lever and said-lamp carriageembodyinga pin and slot.

4. Inan incandescent studio spotlightembodying a lamp :casing having an opening. at its forward end: a mechanism housing on the bottom of andfopeningv inside said lamp casing, a lamp carriage adapted tol support a. lamp within said casing, means supporting and guidingsaid carriage Vfor forward and rearward movement with reference to said lamp casing, said' mechanism housing having front and rear ,walls provided with horizontally extending slots, a focusing lever within said housingV pivotally mounted on a subv stantially vertical axis, said .leverl having oppositely extending arms projecting through'v said horizontallyextending slots, and an. operative interconnection between said'focusing'lever and saidllamp carriage embodying a third arm'on said lever extending substantially at right angles to said first mentioned arms, and a connection between saidfthird arm and the carriage. f

`5.v In an incandescent studio spotlight embodying a lamp casing having an opening at itsffor- Ward end: amechanism housing onl the bottom. of and Vopening insidesaid lamp casing, a lamp: 75,;r

y'sitely extending arms projecting through said horizontally extending slots, and an operative interconnection between said focusing lever and said lamp carriage embodying a third arm on said lever extending substantially at right angles to said rst mentioned arms, and a pin and slot connection between said third arm and the carriage.

CARL R. ERICKSON. 

